HSDPA code settings

[foufou007]

Dear experts,

We are running a max number of HSDPA code allocation of 5 on every cell, this is the default and recommended setting. This setting limit the 16QAM in HSPA+ to 3.6 Mbit/s. What is the implication of setting this parameter to HsPdschMaxCodeNum (Max number of HSDPA codes in a cell) to 15? And why is the recommended value 5?

Thanks

[khurrambilal01]

If the HSPA codes ar set to 5 then HSPA capacity is lesser but if we have 15 HSPA codes enabled then HSPA throughput would be higher and more higher throughput would shrink the coverage of the cell, Thus for a new network which doesn't have much capacity issue so the recommeded value is 5 HSPA codes, But if you want to increase throughput to higher values then you would have to compromise on coverage comparatively by using 15 codes.

[foufou007]

Thanks for the answer, I am actually having downlink CE congestion (before having uplink CE congestions). any ideas what could be the possible trigger?

[khurrambilal01]

How much CEs you have dimensioned in your network for each NodeB?
For some vendors there is feature named "Dynamic CE Resource allocation" and this feature reduces the CE congestion by efficently allocating the required CE according to throughput.

Secondly another feature SRB over HSDPA/HSUPA minimizes the CEs required for HSPA services.

Description of Dynamic CE resource allocation is below:

2.2.2 WRFD-010638 Dynamic CE Resource Management
Availability
This feature is available from RAN10.0.
Summary
To improve the efficiency of CE resources, Huawei RAN introduces the dynamic CE resource management feature. Based on the GBR and actual rate, this feature enables the fast adjustment of CE allocation. When CE resources are preempted, this feature enables the proper allocation of CE resources to ensure the preemption fairness.

2.4.12 WRFD-010652 SRB over HSDPA


Availability
This feature is available from RAN10.0.
This feature is introduced in 3GPP R6.
Summary
SRB over HSDPA enables the DL SRBs of multiple UEs to be carried over HSDPA through the FDPCH multiplexing technology, thus reducing the consumption of DL code resources and the call setup delay.
Benefits
l This feature provides a higher signaling rate and reduces the call process delay.
l Compared with the scenario where the SRB is carried on the DCH, code resources are saved and cell load is reduced when the SRB is carried on HSDPA.

[chefo]

please note that DL CE in HSDPA are used only by A-DCH, and they are not related to the actual HS-DSCH usage.

check the number of active HS users simultaneously in the cell, and the SHO Overhead (overlapping ratio). This would give you the information if your DL CE usage could be due to HSDPA.

what's the value of numHsPdschCodes? do you have dynamic code allocation?

usually you set numHsPdschCodes to 5 and HsPdschMaxCodeNum to 15

also check your RNC and nodeB licenses, what's the allowed number of codes?

[foufou007]

numHsPdschCodes is set to NULL, we have dynamic code allocation on the node B level. The HsPdschMaxCodeNum is set to 5, does that means that I am only allowed to use 5 codes per cell per user? or since the dynamic allocation is activated on Node B level we will be able to provide more than 5 codes thus more throughput per user?

[chefo]

maximum of 15 HS-PDSCH codes can be used in each cell but this can also be limited by the processing resource configurations and installed licenses.
each HSDPA processing resource supports 15 codes in one cell or 15 codes to be shared by three cells. Check how many HSDPA processing resources you have in the nodeB, and then you can calculate the available codes, and hence your HsPdschMaxCodeNum value.